Loom let-off



April 23, 1963 H. HORAK 3,086,560 LOOM LET-OFF Filed March 28, 1961 9Sheets-Sheet 1 INVENTOR HEINZ HO A ril 23, 1963 H. HORAK 3,086,560

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April 23, 1963 H. HORAK Y 3,085,560

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United States Patent 3,086,560 LOOM LET-OFF Heinz Horak, Huttwil,Switzerland, assignor to Apparatefabrilr AG, Huttwil, Switzerland FiledMar. 28, 1961, Ser. No. 98,832 Claims priority, application SwitzerlandMar. 29, 1960 9 Claims. (Cl; 139-110) This invention relates to looms,and in particular to looms including whip rolls supported in movablebearing levers.

In contradistinction to the looms having a rigidly mounted roll thelooms of the particular type contemplated herein are provided withyieldingly supported whip rolls thereby avoiding the drawback of thelooms having a rigidly mounted roll which owing to its manner ofsupport, cannot compensate the differences 'occuring in the warp lengthbetween the Warp beam and the cloth beam and cannot therefore be usedwith a Warp beam driven mechanically. The looms with a rigidly mountedroll are, of course, only suitable for use with simply braked warp beamsfrom which the warp is drawn off intermittently and they have thedisadvantage that with decreasing warp beam diameter, the braking momenthas to be constantly reset manually, in which connection the coefficientof friction is itself a function, among other things, of atmospherichumidity and dust contamination, so that this setting can only beperformed empirically, the more so as, in the absense of a componentmovable in dependence on the warp tension, it is also necessary todetermine the warp tension, and thus the proper timing of theadjustment, manually, by touch.

The looms with yielding supported, or displaceable whip rol-ls which areknown in the art, avoid some of these disadvantages, but the yieldingsupport gave rise to a number of other drawbacks. Thus it was notpossible to determine the extent of the yielding or spring effect whichwould meet all requirements. From the aspect of compensating thevariations of the warp tension when the shed is opened and closed, asoft spring or cushioning action is advisable. A spring or cushioningaction of this type, however, fails to meet the require ment that onimpact of the batten the whip roll should 'be rigid and should evenoppose the motion. Some attempts have already been made to solve thisproblem by increasing the mass of the whip roll which, however, asexperience has shown, involves the danger that rolls begin to vibrate,thus affecting the warp tension in a completely uncontrollable manner.

A hard spring action on the contrary, is undesirable in the interests ofcompensating the shedding action on the warp tension and only partlyprevents the whip roll from yielding on impact of the batten.

Furthermore, since the yielding or displaceably supported whip rollpermanently changes its position according to the variations of the warplength between the warp beam and the cloth beam, it will be observedthat the harder the spring action of the whip roll, the greater thedifferences in the warp tension arising during such changes in position.

The looms known in the art have, in consequence, the commonly shared,essential disadvantages that neither can the initial tension of the warpbe kept even approximately constant, nor is it possible to set thisinitial tension to an absolute, predeterminable value. As known to thoseskilled in the are, this initial tension however plays a de cisive partin regard to the properties of the weave, and an essential requirement,particularly in regard to subsequent processing of the cloth, is notonly that the loom should furnish cloths having the same, accuratelypredetermined, warp tension, but also that it should be pos- '5 ICCsible to adjust a number of looms in such manner that this initialtension has the same, predetermined value in all cases.

Arrangements in which provision has been made for setting said initialtension have already been proposed. With these proposals in which forinstance, springs with adjustable pretensioning are used, it is,however, neither possible to keep the initial tension constant, nor toset it to an entirely predetermined value. The reason for thisinadequacy resides in the spring constant, since the force exerted by aspring is proportional to its deformation, as a result of which, thisforce depends on the position of a warp beam, i.e. is different in eachcase depending on the setting of the whip roll. For this reason, theseproposals cannot possibly succeed in maintaining the initial tension ofthe warp constant since in looms with movably supporter whip rolls, theposition of whip roll depending on the free warp length between the warpand the cloth beams and which could determine the amount of feed of thewarp beam, varies.

Thus the only means for the weaver of determining the initial tensionhas been as yet to judge by hand, with the best possible approximationand from his own experience, whether the Warp tension is, or is not,correct for the particular cloth being made.

To keep the initial warp tension at least in large measure constant, inorder to enable the warp tension to be brought under control in themanner indicated, it has already been suggested to carry the whip rollin movable supporting levers, thereby making it possible to track thefree warp length between the warp and the cloth beam and to adjust thesubsequent advance or feed of the warp beam in terms of this free warplength. In the known arrangements of the latter kind, however, it is notpossible to prevent the initial tension of the warp from varying withthe position of the whip roll. This follows, of course, from a mereconsideration of the forces acting on the whip roll. It in a device, inwhich the displaceably supported unit comprises a single whip roll, theperpendicular distance from th warp thread coming off the warp beam tothe pivot point of the assembly is denoted by a and that of the warpthread running onto the unit or whip roll by b (in a manner similar tothat shown in FIG. 5), then the warp applies a torque to this assemblywhich is proportional to a a-b; with the result that if, during theswinging displacement of the unit or whip roll a decrease, then bincreases, i.e. the value 41-!) and thus the initial tension of the warpvaries very considerably. On account of this dependence of the initialtension of the warp on the position of the whip roll, it is naturallynot possible to keep the warp tension approximately constant.

It is therefore an object of this invention to provide a device adaptedto control and substantially maintain constant, the warp tension.

It is also an object of the invention to ensure the desired adjustmentof the warp tension by means of a weight acting on rockable bearingmeans carrying a pair of whip rolls. i all Another object of theinvention resides in the provision of an assembly operated by saidrockable bearing means to control the warp beam advance in accordancewith the free length of Warp.

A further object of the invention is to associate a damping or brakingdevice with said controlling assembly to suspend temporarily its actionon the warp beam, when the Warp is suddenly subjected to an abruptstress increase, for example upon impact of the batten.

Still further objects of the invention will become apparent from thefollowing description.

One embodiment of the loom improved according to the invention isrepresented diagrammatically and by way of example in the drawingsannexed hereto.

In the drawings:

FIGS. 1 and 1a are two parts of a rear view of this embodiment;

FIGS. 2 and 2a similarly show a plan view thereof;

FIG. 3 is a side view, in the direction of arrow A in FIGS. 1 and 2;

FIG. 4 is a side view in the direction of arrow B in FIGS. 1a and 2a;

FIG. 5 is a diagrammatic representation of the motion gear of saidembodiment;

FIG. 6 is a top view of a driving cam;

FIG. 7 is a diagrammatic representation of the cam control curve andFIG. 8 is a section through a braking device incorporated in saidembodiment.

In the drawings, the rear part of a loom is shown in which the warp beam1 is supported for rotation between two bearing plates 3a and 3b on themachine frame 2. The warp beam is driven by a worm wheel 4 carried onthe shaft 1a of the warp beam which meshes with a worm 6 carried on theshaft 5. The shaft 5 is connected through an overrunning clutch 7 withthe drive pin 8, the overrunning clutch operating in the direction ofrotation causing the warp to unwind from the warp beam. The purpose ofthe overrunning clutch is to transmit the rotary motion of the pin 8 tothe shaft 5 in one direction of rotation only, viz. that of winding offthe warp, there being the further possibility of releasing the clutchbetween the shaft 5 and the pin 8 so that the shaft 5 can be rotated inthe desired direction by the handwheel 9. A bearing stool 10 is securedto the bearing plate 3a, in which the shaft or spindle 12 carrying thebevel wheel 11 is supported for rotation, the said bevel wheel meshingwith a corresponding wheel 13 on the drive pin 8. On the end of thespindle 12 projecting beyond the front face of the bearing stool 10, afree rotary lever collar 14 is fitted having levers 15 and 16, integraltherewith, whereof the first (15) coacts with the push rod 17 workingsynchronously with the loom batten, not represented, and the second(16') is hinged to the drive rod 18. On the same end of the shaft 12, alever 19 is attached which in turn is connected with the control rod 20.

The double-plate bearing frames 21a and 2112 which, among other things,serve to support the control shaft 22, the signifiicance and operationof which will be presently described, are attached above the bearingplates 3a and 3b on the back of the loom to the frame 2. The arm 23 isscrewed to the bearing plate 21a. This arm 23 has two pairs of eyes 24each carrying a slide bar 25, on which slide bars the blocks 26 workmovably. One end of the guide block 27 pivots on the pin 26a of thisslide block, a pin a of the control rod 20 passing into this guide andbeing movably secured there while the drive rod 18 is connected to afixed pivot 27a on this guide block 27. The pin 20a of the control rod20 is held always at a constant distance from the center of the ring 36aby the lever 30 which is supported for free rotation on the cont-r01shaft, by the ring 30a. On the end of the control shaft 22, projectingbeyond the bearing plate 21a a pinion 31 is fixed which meshes with arack bar 2611 on the slide block 26. As a result of this, the pin 20a ofthe control rod 20 is pivotable on the one hand about the rotating pin26:: of the slide block 26 and on the other hand about the center of thering 30a, the extent of the pivoting motion depending on the distancebetween the pins 20a and 26a, i.e. on the relative position of the slideblock 26 with reference to the frame 2 or to the ring 30a, whichrelative position can be varied by moving the slide block 26 Such adisplacement occurs when, in a manner subsequently described, the pinion31 rotates and thus by way of the rack bar 26b moves the slide block 26along the slide bar 25. If now the push rod 17, as stated, reciprocatessynchronously with the loom batten, this reciprocating motion istransmitted by way of the lever 15, the lever collar 14 and the lever 16to the drive rod 18 which consequently swings to and fro synchronously,the guide piece 27 pivoting accordingly on the pin 26a of the sliderblock 26. The pin 20a of the control rod 20 also performs the sameswinging motions with the difference that it reciprocates additionallyin the slide block 26, since, on account of the lever 30, its distancefrom the center of the ring 30a cannot change. Since, in the positionshown (FIG. 4) the pin 20a of the control rod 20 lies nearer the pivotpin 26a of the guide block 27 than the fixed pivot 27a of the drive rod18, all referred to the motion phase shown, the transmittedreciprocating motions of the control rod will be of smaller amplitudethan those of the drive rod 18. The value of this amplitude can bevaried, however, by rotating the control shaft 22, the pinion 31 ofwhich engages in the rack 26b of the slide block 26. In FIG. 4, theslide block 26 is shown in the mid position. If new there is a movementto the left in FIG. 4, then the distance from the pin 20a of the controlrod 20 to the pivot pin 26a of the guide block 27 increases by theaction of the lever 30, by which means the amplitude of thereciprocating motion of the control rod is increased, whereas a movementto the right again results in a reduction of this amplitude, whichfinally falls to zero if the pin 26a is at the same distance from theshaft 22 as the pin 20a. AS a result of this, if, by means of thecontrol shaft 22 or the pinion 31, the slide block 26 is moved, in eachcase depending on the direction of motion, there is a resulting increaseor reduction in the amplitude of the motions of the control rod 20.

The oscillating motions of this control rod 26 are now transmittedthrough the lever 19, the shaft 12 and the bevel wheels :11 and 13 tothe drive pin 8 and the overrunning clutch 7 from which, however, onaccount of the presence of the overrunning clutch, the furthertransmission of the motion takes place in one rotary direction only,viz. that corresponding to winding off the warp, through the shaft 5,the worm 6 to the worm wheel and thus to the warp beam shaft. As aresult of this, by the reciprocating motions of the control rod 20, thewarp beam shaft 1a is rotated stepwise, the amount of this rotationdepending on the amplitude of the oscillating motion of the control rod.This amplitude is, however, also a function of the position of therotating pin 20a of the control rod within the guide block withreference to its pivot point, viz. the pin 26a of the slide block 26.If, consequently, starting from the position shown in FIG. 4, the slideblock is moved to the left by means of the pinion 31 and the rack bar26b by suitably rotating the control shaft 22, then the forward steps ofthe warp beam increase in magnitude, from which it is already clearlyevident that the said rotation of the feed shaft must occur withdecreasing diameter of the warp wound on the warp beam. The manner inwhich this rotation takes place will be described at a later stage.

The shaft 32 carried in the machine frame and rotated by the loom drivealso carries a disc cam 33 which coacts with the roller 36 supported onthe end of the feeler lever 35 for rotation about the pivot point 34.The connecting rod 37 pivots on the same point, and is rigidly connectedto the feeler lever 35 by the angle bracket 38, screws 40 entering inslots 39 in the angle bracket permitting setting of the angle betweenthe two levers 35 and 37, which form a rigid angle lever 35/37. Theother end of the connecting rod 37 is connected at the connecting point41 to the link pin 42 and the latter at the connecting point Win the arm44 of a lever collar 46 fixed on the shaft 45. The shaft or spindle 45is in turn supported on two pivoting members 47 and 48 which are jointlypivotable about the axis of pivot 49 carried at both sides of the rearpart of the machine frame between the pivots of the double-sheet bearingplates 21a and 21b. On the axis 45 is carried the lever 50 connectedwith the one end of the link pin 51 whereas the other end of this linkpin 51 is connected to the bearing lever 52, the other end of whichrotates freely about the axis of pivot 49 of the elements 47/48.Corresponding to the link pin 51 and the bearing lever 52 on the otherside of the machine frame (FIG. 4), a similar link pin 53 and a similarbearing lever 54 are provided, the free end of the link pin beingconnected to an arm 55 corresponding to the arm 50 and arranged torotate about the axis 45, whereas the free end of the bearing lever 54is similarly disposed for rotation about the axis of pivot 49. The twobearing levers 52 and 54 have corresponding bearings 56 and 57, and 5-8and 59, respectively, carrying the shaft 60 of the principal whip roll61 and the shaft 62 of an auxiliary whip roll. An additional fixed guideroll 89 is mounted underneath the auxiliary whip roll 63 and disposed inthe path of the warp threads between the Warp beam and the auxiliarywhip roll in such manner that the warp 76 runs from the warp beam 1 overthe guide roll 89, the auxiliary whip roll 63 and the principal whiproll 61.

The result of this arrangement is that the bearing levers 52 and 54, aswell as the principal whip roll 61, are incorporated in two separatetransmission systems, and thus influenced by two different mechanicallinkages. Thus, the eccentric disc cam 33 causes the rigid, twoarmedlever 35/37 to swing about the pivot 34 and thus through theintermediary of the pushrod 42 causes the lever collar 46 with the pivot45, and thereby through the levers 51 and 53 also the bearing levers 52and 54 with the principal roll 61 and the auxiliary roll 63, to swingaside. A similar, swinging displacement of this system can, however,also be performed by the swing ing arms 47 and 48, viz, in such mannerthat a rotation of these arms about the pivot 49 through theirassociated spindle 45 and the arms or levers 5'0 and 55, as well as therockers 51 and 53, correspondingly rocks the bearing levers 52 and 54about their pivot 49. A turning moment is further exerted on theswinging arms 47 and 48 by the weight 64 which is connected by the steelband 66 passing over the guide-roller 65 with a drum 67 carried on thecontrol shaft 22. The swinging arms 47 and 48 each have an opening orport 68 and 69 respectively, with internal teeth, 70 and 71; the controlshaft passes through these openings or ports and mounts gear wheels 72and 73 meshing with the aforesaid internal teeth 70 and 71 respectively.As a result, the weight 64 in FIG. 3 exerts a clockwise turning momenton the swinging arms. The swinging arm 47 is further associated with adamping device essentially consisting of a piston or plunger 74 and acylinder 75, having a specific, specially selected, dampingcharacteristic (see FIG. 8). The hollow plunger 74 has, below the port74a, a built-in valve 81 urged from below by the spring 82 against itsseat 83 for the purpose of closing the port 88. The plunger head 84 isslidably arranged within the cylinder 75 and penetrated by a bore 85. Anoverflow or bypass is indicated at 86a. The damping device thuscomprises two spaces or chambers, viz. a first chamber 86 comprising thespace over the plunger head 84 and communicating with the space formedby the hollow portion of plunger 74 through the port 74a; and a secondspace or chamber 87, below the valve 81 and plunger head 84. The twochambers 86 and 87 are continuously in communication through the bore 85and, when the valve is open, through the port 88. In the openingposition, both chambers 86 and 87 are filled with a working fluid, e.g.oil. If the plunger is now drawn upwards, a pressure-drop occurs in thechamber 87, the valve 81 opens the port 88, and pressure-equalizationtakes place between the two spaces or chambers without perceptibleretardation of the upward motion, through the aforesaid port. When theplunger is driven inwards, on the other hand, the valve 81 is forced bythe pressure rise in the chamber 87 against its seat 83, so that theequalization of the pressure between the spaces or chambers 86 and 87now takes place solelythrough the bore 85. Consequently, slow,descending motions of the plunger can take place without any substantialretardation or braking effect; while more abrupt downstrokes, exceedinga certain speed, are effectively braked or damped.

The motions of the bearing levers 52, 54, deriving from the disc cam 33,and those imparted by the swinging arms 47, 48, are not to be allowed toinfluence each other. This condition is only fulfilled when the twocircular arcs described from the centers 41 and 49 through the hingepoint 43 are practically coincident through a sufliciently large range.In the arrangement represented here, this is attained to a practicallysufficient extent by placing the two centers 41 and 49 very closetogether, so that the circular are described during rotation of the disccam 33 from the center 34 through the hinge point 41 cuts the axis 49,the pin 41 swinging about this intersection point approximately equallyin either direction; and, further, by seeing to it that the tangent tothe said arc in this point of intersection coincides with the directionof motion of the pushrod 42, when the swinging arms 47, 48 are in themidposition, i.e., slightly lower than shown in FIGS. 3 and 4.

From this description of the arrangement it will be seen, omitting fromconsideration the control action of disc cam 33 which merely representsan additional refinement, that the swinging arms 47 and 48 on the onehand receive a turning moment M imparted by tension of the warp threads76 running over the principal whip roll 61 and the auxiliary whip roll63, and wound on the warp beam 1, through the intermediary of thebearing levers 52 and 64, the link pins 51 and 53, and the arms 50 and55; and on the other hand are acted upon by an opposed, constant torqueB, exterted by the weight 64 through the gear wheels 72 and 73. In thealways selfadjusting equilibrium position, M =B=const. However, therelationship M=K(ab) (see FIG. 5) also applies, in which K is the warptension (it is assumed for the sake of simplicity that the two forcesacting on the assembly formed by the principal whip roll and theauxiliary whip roll, in the direction of the warp threads running offthe principal whip roll, and in the direction of the Warp threadsrunning on to the auxiliary whip roll, are equal), a the distance of thewarp threads running off and b the distance of the warp threads runningon, from the common axis of rotation 41. In other words,

i.e., is inversely proportional to the difference of the two,above-named distances; so that the warp tension can only be heldconstant if within the potential range of swing of the principal andauxiliary whip rolls, the difference a-b can 'be held constant at leastapproximately. By the manner selected of supporting the principal whiprolls 61 and the auxiliary whip rolls 63 in the same bearing levers 52and 54, it has been possible to make the ratio of the geometric leverarms a and b such that the difference (a-b) remains practicallyconstant, despite rotation of the bearing levers and, additionally, inview of the provision of the fixed guide-roller or drum 89,substantially independent of the instantaneous diameter of the warpbeam. In order to enable a prescribed warp tension value to be adjustedat any time without difliculty, a suitable relationship must beestablished between the tensioning weight and the tensioning force onthe warp threads. In the exemplary embodiment shown, this transmissionratio has been fixed at 1:10, for which reason, in view of therestricted space available, internal gearing has had to be used for theswinging arms 47, 48 (B-(a-b)='l 0G). Accurately dimensioned slabweights of 5, 2, 1 and 0.5 kg. enable in practice and adjustment of thewarp tension to be obtained, variable stepwise in units of 5 kg. If, forexample, the warp tension is too low, and M B, then the swinging anmstogether with the principal whip roll 61 and the auxiliary whip roll 63,in

agoaaseo FIG. 3, rotate clockwise, whereby the warp is tensioned, theturning moment M increases, and the displacement of the whip rollassembly ceases only when equilibrium has been established between thetwo turning moments, and the required warp tension, as adjusted by thedimensioning of the loading weights, has become established. At the sametime, this rotatory displacement remains substantially unaffected by thedamping device 74/75 since it causes the plunger 74 to move outwards,which, as already explained, takcs place practically without resistance.If, from this equilibrium condition, the warp tension rises furtherduring weaving, and consequently M B, the whip roll 61 swings, i.e. thearms 47 and 48 in FIG. 3 turn anticlockwise, which swinging motion,however, depending on the speed with which it takes place, is braked orretarded by the damping device 74/75. Should an occasional increase inthe turning moment M be produced, for instance, by an inadequate advanceof the warp-beam, the corresponding swinging motions of the arms 47 and48 take place without encountering any substantial resistance, sincesuch displacements and in fact all movements produced by the usualfluctuations of the warp tension take place only very slowly.

In the presence of abrupt and brief changes in the warp tension, such asthose caused by the impacts of the batten, the damping device 74, 75 hasan entirely different effect in that it completely brakes the swingingarms, so that the impacts of the batten cannot cause any displacement,either of the swinging arms 47, 48, the whip roll 61, or the weight 64.

As a result, the arrangement described, enables the swinging arms to belocked in the case of an abrupt and brief rise of the warp tension,while a slow, gradual increase in the warp tension causes the swingingarms 47, 43 in FIG. 3 to turn counterclockwise. This motion, actingthrough the internal gears 70 and 71 and the gear wheels 72 and 73,causes a rotation of the control shaft 22, viz., in FIG. 3counterclockwise and in FIG. 4 clockwise. As already mentioned earlier,such a rotation of the control shaft displaces the sliding block 26(FIG. 4) to the left and thereby moves the control-rod pin a inside theguide block 27, viz. in FIG. 4, to the right. This increases thedistance between this pin 20a and the pivot pin 26a, and, consequently,the length of stroke of the up and down motion of the control rod 20,whereby, as already stated, the forward feed advance of the warp beam isalso increased. This causes the run-off of the warp 76 from the warpbeam 1 to become greater, so that the warp tension and thereby also theturning moment M are diminished. A contrary motion of the swinging arms47 and 48 and therewith of the whip roll 61, produced by the action ofthe weight 64, now restores the equilib rium of the system. Thus, in thearrangement described, the whip roll, which is made to performcontrolled motions for the purpose of balancing the warp tension whenthe shed is opened and closed, is also movably supported in such manneras to be able to control the warp tension, and finally, on theoccurrence of the abrupt but very brief rise in tension caused by theimpacts of the batten, behaves practically as if it were fixed in place.

In addition, however, the whip roll can also be separately controlled bythe action of the disc cam, viz. through the intermediary of the leversand guides 35, 37, 42, 44, 50/53, in particular, under the conditionalready stated, concerning the reciprocal positions of the track of thehinge point 41 and the axis of rotation 49.

Such a positive control of the whip roll is particularly desirable inregard to the need both for balancing the warp tension when the shed isopened and closed and for providing a strong warp holding during theimpacts of the batten. In the first instance, the fluctuations in thethread tension produced by the opening and closing of the shed aresmoothed out; in the second case, a strong holding of the warp isensured when the reed of the batten is beating up the weft to the fellof the cloth.

FIG. 6 shows a correspondingly profiled disc cam or carn plate 33, andFIG. 7 the curve of the force exerted thereby on the whip roll assemblyduring two revolutions of the cam shaft, in relation to the angulardisplacement of this cam plate. The circular segment portion of the camprofile 77 produces no additional action on the whip roll assembly; thecam segment 78 produces at the instant of closing the shed a steadilyincreasing swing of the whip roll assembly, in FIG. 3 clockwise, aboutthe pivot point 49, i.e. an increasing pull on the warp until the shed79 has closed; while the segment 80 finally exerts a brief counter-pullsynchronised with the reed beating the weft.

Thus, the invention succeeds in providing a whip roll assembly adaptedfor being positively controlled to compensate for the shedding action,which is yieldably, or displaceably, supported so as to be capable ofcontrolling a mechanically driven warp beam, and considering a different aspect, a whip roll arrangement of this kind which is subject toan additional positive control whereby to ensure a substantiallyconstant tension of the warp, capable of being regulated to apredetermined, absolute value.

Although one embodiment of my invention has been described in detailwith reference to the accompanying drawings, I wish it to be understoodthat various changse in the shape, sizes and arrangement of parts can beresorted to within the scope of the appended claims and withoutdeparting from the spirit or sacrificing the advantages of theinvention.

I claim:

1. A loom including a warp beam and a warp tension control device whichcomprises a bearing means supported for rocking and pivotaldisplacement, a principal whip roll having an axis extending in parallelto the axis of the warp beam, mounted on said bearing means, and anauxiliary whip roll having an axis extending in parallel to the axes ofthe principal whip roll and the warp beam, mounted on said bearing meansand disposed in the path of the warp threads fed from the warp beam tothe principal whip roll, between said warp beam and said principal whiproll.

2. A loom including a warp beam and warp tension control device whichcomprises a bearing means supported for rocking and pivotaldisplacement, a principal whip roll having an axis extending in parallelto the axis of the warp beam, mounted on said bearing means, anauxiliary whip roll having an axis extending in parallel to the axes ofthe principal whip roll and the warp beam, mounted on said bearing meansand disposed in the path of the warp threads fed from the Warp beam tothe principal whip roll, between said warp beam and said principal whiproll, and a fixed guide roll having an axis extending in parallel to theaxes of the warp beam and the principal and auxiliary whip rolls,disposed in the path of the warp threads fed from the warp beam to saidauxiliary and principal whip rolls, between said warp beam and saidauxiliary whip roll.

3. A loom including a warp tension control device according to claim 2,wherein a plane through the pivotal axis of the bearing means and theaxis of the principal whip roll, extends at substantially right anglesto the plane in which the warp threads run off the principal whip roll,and a plane through the pivotal axis of the bearing means and the axisof the auxiliary whip roll, extends at substantially right angles to theplane in which the warp threads travel from the fixed guide roll to theauxiliary whip roll.

4. In a loom including a warp tension control device according to claim2, a warp beam feed control device comprising swinging arms connectedwith said bearing means, and a damping device adapted to yield to slowvariations in the warp tension but to effectively brake said warp bearnfeed control device in response to sudden variations in the warptension.

5. A device according to claim 4, wherein said damping device isprovided as a hydraulic mechanism including a piston, a check valvecontrolled main passage in said piston, and a narrow bore also in saidpiston, chambers above and below said piston, and working fluid adaptedto pass from one to the other of said chambers through the said passageand said bore, respectively.

6. A device according to claim 4, comprising a weight influencing saidswinging arms, the turning moment imparted by said weight to saidswinging arms 'being opposed to the turning moment imparted to theswinging arms by said bearing means in response to the warp tension.

7. A device according to claim 4, wherein the bearing means and theswinging arms pivot about the same axis.

8. A device according to claim 4, wherein the swinging arms compriseinternal gears, a shaft controlling the feed of the warp beam, and gearson said shaft meshing with said internal gears.

9. A device according to claim 8, comprising a weight influencing theswinging arms, and a drum mounted on the shaft controlling the feed ofthe warp beam, said weight acting directly on said drum.

References Cited in the file of this patent UNITED STATES PATENTS

1. A LOOM INCLUDING A WARP BEAM AND A WARP TENSION CONTROL DEVICE WHICHCOMPRISES A BEARING MEANS SUPPORTED FOR ROCKING AND PIVOTALDISPLACEMENT, A PRINCIPAL WHIP ROLL HAVING AN AXIS EXTENDING IN PARALLELTO THE AXIS OF THE WARP BEAM, MOUNTED ON SAID BEARING MEANS, AND ANAUXILIARY WHIP ROLL HAVING AN AXIS EXTENDING IN PARALLEL TO THE AXES OFTHE PRINCIPAL WHIP ROLL AND THE WARP BEAM, MOUNTED ON SAID BEARING MEANSAND DISPOSED IN THE PATH OF THE WARP THREADS FED FROM THE WARP BEAM TOTHE PRINCIPAL WHIP ROLL, BETWEEN SAID WARP BEAM AND SAID PRINCIPAL WHIPROLL.